In Texas, 17-year-olds are treated as adults for purposes of criminal law, which previously meant that those convicted of capital murder were eligible for one of two punishments: death or life in prison without the possibility of parole. But the Supreme Court ruled both punishments unconstitutional for suspects younger than 18 -- capital punishment in 2005, and mandatory life without parole in 2012 -- so the legislature said that 17-year-olds can only be sentenced to life with the possibility of parole.

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Texas' highest criminal court gave its answer on Wednesday. Even for teens convicted before the Supreme Court's 2012 decision, a mandatory sentence of life without parole is unconstitutional.

The Texas Court of Criminal Appeals' ruling came in the case of Terrell Maxwell, who was convicted of capital murder in Travis County in 2007.

According to the court's summary of the case, he and some friends were "smoking weed and watching movies" when they decided to rob someone. As they waited in a car at an Austin apartment complex, Maxwell announced that he would shoot their victim if he refused to give them money, which is what happened: he fatally shot a man they found sitting in a parked van, who responded to their demands for cash by putting up his hands in shock.

Because the Supreme Court had already taken the death penalty off the table, Maxwell was automatically sentenced to life without parole.

Logically, it would seem that the Supreme Court's ruling that a juvenile's mandatory life sentence in 2012 was unconstitutional would make all such sentences unconstitutional. But as the Texas court's narrow 5-4 split suggests, it's not quite that simple.

Ultimately, the majority writes, that decision is up to the Supreme Court. But "looking into the crystal ball, we think that the Supreme Court will hold that ...[this] is a "new substantive rule" that puts a juvenile's mandatory 'life without parole' sentence outside the ambit of the State's power."

To be clear, this doesn't mean that Maxwell and other juvenile offenders can't be sentenced to life without parole. That's still a possibility, "after consideration of applicant's individual conduct, circumstances, and character." It just can't be mandatory.